1. Technical Field
The present invention relates to an image forming device in which can be installed an image forming material cartridge which contains an image forming material such as toner, ink, or the like, and which has a non-volatile memory which can be written and read; and, in particular, relates to a technique for determining upon refilling such an image forming material cartridge with image forming material.
2. Related Art
In the past, it has been possible to install a toner cartridge in which toner for forming images is contained into an image forming device which performs image forming such as printing or the like. And, when the toner which was contained in the toner cartridge has been used up, it becomes possible to perform further image forming by exchanging the cartridge for a new toner cartridge.
In recent years, sometimes a refilled product which is made by recharging (refilling) toner into a toner cartridge which has been used up has been installed in an image forming device and used.
Accordingly, if a refilled product is used, it is necessary to urge the user to take care about the existence of this type of possibility.
Due to this, for example, it has been practiced to keep a running total of a toner usage amount count which roughly indicates the actual toner usage amount, and, when this exceeds a predetermined threshold value, to determine that this is a refilled product, and to urge the user to take care. As such a toner usage amount count, a physical quantity is used which is considered to be strongly related to the amount of toner consumed (i.e. to the toner usage amount), for example the number of dots which have been printed, the rotational speed of a motor for supplying toner to a development unit, the period of time such a motor has been driven, or the like.
As a technique for detecting refilling, for example, a technique is known (refer to JP-A-2002-331686) of recording processing in which the amount of ink decreases, and, if the amount of ink has increased although the ink container has not been exchanged, issuing a warning to the effect that, it is not possible to guarantee normal printing, since the ink has been refilled.
However, with the invention described in JP-A-2002-331686, there is the problem that it is necessary to provide a structure for detecting the actual remaining amount of ink. For example, it is extremely difficult to detect the remaining amount of toner in a toner cartridge, so that it is extremely difficult to provide a structure for doing so.
On the other hand, if it is arranged to keep a running total of a toner usage amount count from the start of use, and to determine that the cartridge is a refilled product if this has exceeded a predetermined threshold value, then the following type of problem arises.
For example it has been considered to take, as the threshold value, a value which cannot normally be arrived at. However, since such a toner usage amount count is not the actual usage amount of the toner itself, but rather is something which roughly indicates the toner usage amount, such as a physical quantity like, as mentioned above, the number of dots which have been printed, the rotational speed of a motor for supplying toner to the development unit, the period of time such a motor has been driven, or the like. Accordingly there is a fear that the correspondence relationship between the toner usage amount count and the actual amount of toner consumption will be very much different, depending upon the circumstances of use by the user. In other words there is a fear that, depending upon the circumstances of user the actual amount of toner consumed may be greatly different, so that the remaining amount of toner may be greatly different, even though the toner usage amount count may be the same.
Due to this, even if the toner usage amount count is at a value of 150% of the toner usage amount count at which it is supposed that, with normal usage, the toner is used up, nevertheless, due to the circumstances of usage, it might be the case that some toner is left remaining. Accordingly, if a value of 150% of the toner usage amount count at which it is supposed that, with normal usage, the toner is used up, is taken as being the threshold value, then the possibility exists of mistakenly deciding that a toner cartridge which has not been refilled is a refilled product.
In order to prevent the occurrence of this type of mistaken decision, it is necessary to set the threshold value to be a large value, but, even if this is done it is difficult perfectly to prevent mistaken decisions, unless the threshold value is extremely large.
On the other hand, if the threshold value is set to be a larger value, then it becomes possible to suppress the occurrence of mistaken decisions to a comparatively large extent, but, since a considerable time period is required until the toner usage amount count arrives at the threshold value, accordingly, even if the subject cartridge is a refilled product, this considerable time period will elapse until it is determined that it is a refilled product, so that there is a fear that the message urging the user to take care will be undesirably delayed.
Moreover, in recent years, sometimes rental of a toner cartridge to the user is performed. In this case, in the rental contract for the toner cartridge, sometimes a clause is also incorporated, for example, specifying that refilling should not be performed. In this type of case, there is a requirement to prevent improper usage outside the scope of the rental contract; in other words there is a requirement to prevent usage in which this toner cartridge, which is a rental product, is refilled. Moreover, it may be considered to use both a rental product and a purchased product in parallel in the image forming device, and in this type of case as well, there is a requirement to prevent, in an appropriate manner, unauthorized use of the rental product.